emgcr wrote:This may not suit your project but, for interest, here is a sketch of the salient measurements of an EMG horn spigot made in bronze. As you will see, the internal diameters are different at both ends in order to follow what becomes the exponential progression.
I may be able to incorporate this into my project I did want to ask about this though. If the tone arm opens up into a straight metal pipe and which does a U turn at the bottom of the cabinet so that the metal pipe in the paper horn can be dropped onto the internal pipe..... is it bad if it’s not exponential?
That should be fine as at the smaller diameters an EMG conduit is conical right from the swinging swan-neck or goose-neck---exponential only starts in the horn which you have already made. The conduit should ideally be as solid as possible and made of a non-resonant material. If you can only find thin-wall conduit it would be a good idea to lag it to kill unwanted frequencies. An EMG tonearm is cast for similar reasons. You are endeavouring to transmit only the frequencies on the record grooves without interference from anything else.
On second thoughts, emgcr is right about the weight concern. Unless you have a generous length of the narrow end strongly reinforced, gesso might not be a good idea after all.
dzavracky wrote:What did you use for the final coat?
Where can I get paper like that? I was planning on re-enforcing the entire horn before trying the gesso. The inside of the bell needs quite a bit of attention.
David, the Achilles heel of your horn is bound to be around the first bend where the maximum torque is exerted by the bell. You may like to investigate the various thin Kevlar fabrics which are available which will dramatically increase structural strength and stability ? The EMG Xb Oversize horns have aluminium castings at this vulnerable and critical location. If you strengthen the bend you will also give yourself the opportunity of adding bell weight with the gesso.
That handmade marbled paper is absolutely gorgeous.
David, I betcha shelf paper/contact paper would do the trick for a few first attempts, after gesso. You can get a walnut-burled shelf paper that would be nice. Also, shelf paper is usually vinyl-coated nowadays, and that would be easier to dust (always a consideration with outside-horn phonographs. After buying a couple I got very familiar with just why the Victrola was invented to replace them!)
The ideas on reenforced horn material make me wonder, David, if it wouldn't do better to build another horn with a little more structural umph to it. I think the difference is, in material (at least the old EMG paper horns and your new replica) is that the originals look to have been made of torn strips. That would let you layer them up almost like a grain, instead of using leaves of newsprint. Cabbages are also made of leaves, and they do wilt if you're not careful LOL.
As for this new horn, I think you could rig a driver out of a small Bluetooth cube speaker, and build the ultimate in digital sound: hang it from a corner of the record room like the old talking-picture apparatuses from the movie house, run a wire to it for charging, and stream your records into it. Or rig a way to hook it up to your electric amplifier & play vinyl records & reel-to-reel tape through it--I guess that'd work best with monaural recordings. That would be the biggest horn anyone ever put on a modern electric turntable.
If only someone would start making new full-size gramophone motors & reproducers again I think between the horn thing here, Mr Wilson's 78s, Vulcan, and other companies, that there could be an acoustic revival and then, only then, I might be induced to buy a brand-new record player for once. But that is a pipe dream.
dzavracky wrote:Where can I get paper like that? I was planning on re-enforcing the entire horn before trying the gesso. The inside of the bell needs quite a bit of attention.
David
I got mine here in England from a small firm called Jemma Lewis Marbling - it cost me around £40, ending up with around one-third left over. There are a few other suppliers of marbled paper here, I'm not sure about the States though. Leatherette or reptilian textured paper would be another option if you can find some.
Silly question perhaps, but why not use a coating of fibreglass auto body filler with the thin reinforcing cloth between paper layers? That should add tons of stability but not too much weight.
"He who dies with the most shellac wins"- some nutty record geek
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I did want to ask about this though. If the tone arm opens up into a straight metal pipe and which does a U turn at the bottom of the cabinet so that the metal pipe in the paper horn can be dropped onto the internal pipe..... is it bad if it’s not exponential?
